NFSD: Update READ3arg decoder to use struct xdr_stream

The code that sets up rq_vec is refactored so that it is now
adjacent to the nfsd_read() call site where it is used.
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>

fs/nfsd/nfs3proc.c

@@ -144,25 +144,38 @@ nfsd3_proc_read(struct svc_rqst *rqstp)
 {
 	struct nfsd3_readargs *argp = rqstp->rq_argp;
 	struct nfsd3_readres *resp = rqstp->rq_resp;
-	u32	max_blocksize = svc_max_payload(rqstp);
-	unsigned long cnt = min(argp->count, max_blocksize);
+	u32 max_blocksize = svc_max_payload(rqstp);
+	unsigned int len;
+	int v;
+
+	argp->count = min_t(u32, argp->count, max_blocksize);
 
 	dprintk("nfsd: READ(3) %s %lu bytes at %Lu\n",
 				SVCFH_fmt(&argp->fh),
 				(unsigned long) argp->count,
 				(unsigned long long) argp->offset);
 
+	v = 0;
+	len = argp->count;
+	while (len > 0) {
+		struct page *page = *(rqstp->rq_next_page++);
+
+		rqstp->rq_vec[v].iov_base = page_address(page);
+		rqstp->rq_vec[v].iov_len = min_t(unsigned int, len, PAGE_SIZE);
+		len -= rqstp->rq_vec[v].iov_len;
+		v++;
+	}
+
 	/* Obtain buffer pointer for payload.
 	 * 1 (status) + 22 (post_op_attr) + 1 (count) + 1 (eof)
 	 * + 1 (xdr opaque byte count) = 26
 	 */
-	resp->count = cnt;
+	resp->count = argp->count;
 	svc_reserve_auth(rqstp, ((1 + NFS3_POST_OP_ATTR_WORDS + 3)<<2) + resp->count +4);
 
 	fh_copy(&resp->fh, &argp->fh);
 	resp->status = nfsd_read(rqstp, &resp->fh, argp->offset,
-				 rqstp->rq_vec, argp->vlen, &resp->count,
-				 &resp->eof);
+				 rqstp->rq_vec, v, &resp->count, &resp->eof);
 	return rpc_success;
 }
 

fs/nfsd/nfs3xdr.c

@@ -389,31 +389,17 @@ nfs3svc_decode_accessargs(struct svc_rqst *rqstp, __be32 *p)
 int
 nfs3svc_decode_readargs(struct svc_rqst *rqstp, __be32 *p)
 {
+	struct xdr_stream *xdr = &rqstp->rq_arg_stream;
 	struct nfsd3_readargs *args = rqstp->rq_argp;
-	unsigned int len;
-	int v;
-	u32 max_blocksize = svc_max_payload(rqstp);
 
-	p = decode_fh(p, &args->fh);
-	if (!p)
+	if (!svcxdr_decode_nfs_fh3(xdr, &args->fh))
+		return 0;
+	if (xdr_stream_decode_u64(xdr, &args->offset) < 0)
+		return 0;
+	if (xdr_stream_decode_u32(xdr, &args->count) < 0)
 		return 0;
-	p = xdr_decode_hyper(p, &args->offset);
-
-	args->count = ntohl(*p++);
-	len = min(args->count, max_blocksize);
-
-	/* set up the kvec */
-	v=0;
-	while (len > 0) {
-		struct page *p = *(rqstp->rq_next_page++);
 
-		rqstp->rq_vec[v].iov_base = page_address(p);
-		rqstp->rq_vec[v].iov_len = min_t(unsigned int, len, PAGE_SIZE);
-		len -= rqstp->rq_vec[v].iov_len;
-		v++;
-	}
-	args->vlen = v;
-	return xdr_argsize_check(rqstp, p);
+	return 1;
 }
 
 int

fs/nfsd/xdr3.h

@@ -32,7 +32,6 @@ struct nfsd3_readargs {
 	struct svc_fh		fh;
 	__u64			offset;
 	__u32			count;
-	int			vlen;
 };
 
 struct nfsd3_writeargs {